Heat exchangers are in wide use which comprise a pair of aluminum headers arranged in parallel as spaced apart from each other, a plurality of flat heat exchange tubes of aluminum serving as hollow refrigerant channel portions, arranged in parallel between the pair of headers and having opposite ends jointed to the respective headers, and corrugated aluminum fins arranged in respective air passing clearances between respective adjacent pairs of heat exchange tubes and each joined to the pair of heat exchange tubes adjacent thereof.
The flat heat exchange tube comprises, for example, two flat walls positioned in parallel to each other, opposite side walls interconnecting the two flat walls respectively at opposite side edges thereof, and a plurality of reinforcing walls interconnecting the two flat walls, extending longitudinally thereof and arranged at a predetermined spacing between the opposite side walls, the heat exchange tube having parallel fluid passageways in the interior thereof, each of the reinforcing walls comprising a reinforcing wall ridge projecting inward from one of the flat walls and formed integrally therewith and a reinforcing wall ridge projecting inward from the other flat wall and formed integrally therewith, the reinforcing wall ridges being butted against and brazed to each other, the portions of the wall ridges brazed to each other providing an inside joint. (see the publication of JP-A No. 6-281373).
For the heat exchanger described above and comprising the flat heat exchange tube to have the required heat resistance, the reinforcing wall ridges need to be brazed to each other with a sufficient strength and free from brazing faults.
However, it is not easy to detect faults in the portions of the reinforcing wall ridges brazed to each other, i.e., in the inside joint, and the strength of the brazing joint between the wall ridges, and consequently it is presently impossible to inspect the heat exchanger for pressure resistance easily.
An object of the present invention, which has been accomplished in view of the above situation, is to provide a method of and an apparatus for inspecting heat exchangers for pressure resistance relatively easily and accurately.